Basically, the smart phones in market are equipped with a light sensor, for automatically adjusting a screen's brightness, and a proximity sensor, for sensing the distance between a user's face and the screen while the user is making a phone call through the smart phone. Thus, through the employment of light sensor and a proximity sensor, smart phone can automatically turn off the screen thereof while the user is using the smart phone for talking and thereby prevent misoperations while the user's face is touching to the screen. In addition, it is understood that tablet or e-book may be also equipped with the light sensor.
In addition, smart phones are also equipped with a protective glass having a hole structure. The hole structure is designed for receiving a specific range of wavelength and having a specific light transmittance based on the models or specifications of the employed light sensor and proximity sensor. In other words, the performances of light sensor and proximity sensor are directly related to the light transmittance of the hole structure of the protective glass under a specific light beam. Thus, the measurement for determining whether the light transmittance of the hole structure of the protective glass under a specific light beam (for example, visible light and near-infrared light) is qualified or not is particularly important.
However, the existing light transmittance measuring apparatuses have lower measurement accuracy due to are designed without considering much about the impact of external ambient light. In addition, the existing light transmittance measuring apparatuses have a lower production efficiency due to unable to measure the light transmittances of the hole structure of protective glass under two light beams with different wavelength ranges (for example, the green light and the near-infrared light) at the same time; in other words, the two different light beams are needed to be measured individually. Furthermore, the existing light transmittance measuring apparatuses have a lower compatibility due to are customized; in other words, the existing light transmittance measuring apparatuses are needed to be redesigned for another type of object to be tested.